public class  PerimeterAreaOfCircle
{
	final static double PI=3.1415926;    //定义常量PI
	public static void main(String args[]) 
	{
		double r,perimeter,area;
		r=Double.parseDouble(args[0]);
		/*从命令行读入的字符串args[0]转换为实型double*/
		perimeter=2*PI*r;
		area=PI*r*r;
		System.out.println("圆的周长为："+perimeter);  //实现字符串的输出
		System.out.println("圆的面积为："+area);       
	}
}
